In certain petrochemical reactions the use of supported catalysts having most of their pores in diameters less than about 100 .ANG. can present many problems. Diffusional limitations can occur when reactions take place in very small pores. Many petrochemical feedstocks contain various metal impurities such as nickel, vanadium or iron which can deposit out and poison small pore sized materials. Thus, catalysts having large average pore diameters, particularly catalysts having average pore diameters above about 100 .ANG., have been found to have greater metals capacity than catalysts having substantially only relatively small pores. Methods for creating controlled pore sizes in aluminas are hence quite useful. Various means have been utilized in the art to prepare supports with controlled pore sizes. Carbonaceous materials have been incorporated in aluminous material which, upon burn-out, produce selected pore sizes. Another means utilized has incorporated various fine solid particles, such as recycle catalyst fines into the processing of the alumina. Detergents have been added to hydrogels, which upon extrusion resulted in wide pores.